Study On Key Technologies Of Internet-based Virtual Reality Combining Images And Models

Virtual Reality (VR) can be defined as the simulation of the real world,including the 3-dimensional geometry space,1-dimensional time and the immersive or semi-immersive interaction interface. Applying VR technologies to the process of industry product design has been proved to be impactful. PC-based VR technologies are becoming popular research areas due to the rapid development of computer technologies and the popularization of using computer.There are two methods to implement a PC-based VR scene:the image-based method (IBM) and the model-based method (MBM). Both of them have their advantages and disadvantages. For examples:Although IBM has good realistic effects and good real-time capability,a virtual scene built by IBM can not been manipulated. MBM supports real-time manipulation,however,it faces some difficulties such as dynamic modeling,collision detection,etc.In recent years,the rapid development of Web technology provides the possibility to implement an Internet-based multi-user distributed VR system. The objective of this research is to study respectively on the theories and implementations of IBM VR and MBM VR,the technologies of Internet-based real-time rendering and the combination of IBM VR and MBM VR to implement an Internet-based VR system combining images and models. This system combines the advantages of IBM and MBM.This research belongs to the category of the research of application foundation. The major research results are following:(1) This research presents a feasible method for 3D reconstruction,requiring only a digital camera and a personal computer,with which the image-based 3D automatic reconstruction is achieved.(2) The method of images subsection interpolation,by which an image-based 3D reconstruction and virtual navigation system is developed,is presented to solve the perspective consistency problem of virtual navigation.(3) A category-based dynamic graph.(CDG) structure,which supports the novel tactic of relation-oriented collision detection,is presented to improve the efficiency of collision detection and realize the attached motion in VR scene.(4) A dynamic 8-tree structure and a relative self-similar recursion algorithm are presented to model a dynamic workpiece object,which is machinable.(5) Some novel tactics,such as a vision sensitivity-based arrangement tactic of level of details,are presented to improve the real-time rendering efficiency of the VR system. An image-based virtual workshop and a model-based virtual CNC milling machine are developed.(6) An Internet-based virtual machining system,which is the integration of the image-based virtual workshop and the model-based virtual CNC milling machine, is constructed using the reposition method to achieve the visual consistency of the virtual objects and images. This system combines the advantages of image-based VR and model-based VR. Consequently,this system has both high rendering quality and good real-time interactivity,and thus has a very good application perspective.